Outage Probability Analysis of Uplink NOMA over Ultra-High-Speed FSO-Backhauled Systems

TL;DR

This paper analyzes the outage probability of uplink NOMA systems with FSO backhaul, deriving formulas for performance under Rayleigh fading and Gamma-Gamma turbulence, highlighting the integration of NOMA with high-speed FSO links.

Contribution

It introduces the first analytical outage probability expressions for uplink NOMA over RF-FSO mixed systems with turbulence and pointing errors.

Findings

Closed-form outage probability formulas derived

Performance impacted by FSO turbulence and pointing errors

NOMA can be effectively integrated with high-speed FSO backhaul

Abstract

In this paper, we consider a relay-assisted uplink non-orthogonal multiple access (NOMA) system where two radio frequency (RF) users are grouped for simultaneous transmission, over each resource block, to an intermediate relay which forwards the amplified version of the users' aggregated signals in the presence of multiuser interference to a relatively far destination. In order to cope with the users' ever-increasing desire for higher data rates, a high-throughput free-space optics (FSO) link is employed as the relay-destination backhaul link. Dynamic-order decoding is employed at the destination to determine the priority of the users based on their instantaneous channel state information (CSI). Closed-form expressions for the individual- and sum-rate outage probability formulas are derived in the case of independent Rayleigh fading for the users-relay access links when the FSO backhaul link is subject to Gamma-Gamma turbulence with pointing error. This work can be regarded as an initial attempt to incorporate power-domain NOMA over ultra-high-speed FSO-backhauled systems, known as mixed RF-FSO systems.